Healthy Heart Information for American Heart Month

February is American Heart Month, and MDF has partnered with Drs. Katharine Hagerman and Marianne Goodwin to highlight important research on cardiac issues in myotonic dystrophy for our community.

Researchers in the lab of William Groh, MD, at Indiana University have been studying heart involvement in myotonic dystrophy type 1 (DM1), including heart conduction defects, cardiac rhythm disturbances, and structural heart abnormalities for some time. The group performed cardiac imaging and analysis of the electrical impulses of the heart by electrocardiography (ECG or EKG) on individuals with DM1, and found that certain structural changes in the heart are increased in individuals with cardiac electrical abnormalities. In addition, the study identified predictors of heart failure and dysfunction, including increased age and changes in electrical conduction of the heart observed by ECG, specifically measurements known as PR interval and QRS duration. These indicators may be used by doctors to help predict which DM patients would benefit most from implantable cardiac rhythm devices such as pacemakers. Additionally, the group found that some individuals with DM1 benefit more from devices known as implantable cardioverter-defibrillators (ICDs) than standard pacemakers to help correct heart rhythm disturbances.

The heart involvement in myotonic dystrophy type 2 (DM2) is similar to that seen in DM1, however controversy exists over the frequency and severity of heart irregularities in the DM2 population. To address this, a research team led by Giovanni Meola, MD, in the Neuromuscular Clinic at IRCCS Policlinico San Donato in Italy compared cardiac abnormalities in DM1 and DM2. Using tests such as ECG and echocardiography, the study found that heart involvement is less common and generally milder in DM2 than DM1. However, individuals with DM1 and DM2 are both at increased risk of heart abnormalities such as cardiac arrhythmias and conduction disturbances. These heart irregularities can be progressive with age, and may be present in individuals even when no symptoms are experienced. Therefore, people living with DM should receive annual cardiac evaluations, including ECG, by primary care physicians or cardiologists to promote heart health.